With the increasing development of semiconductor industries, highly-integrated electronic appliances and high-performance electronic appliances need to be developed, such that electronic devices serving as the core components of the electronic appliances also need to be highly integrated with high-level performances. However, as an integration degree of the electronic devices increases and a unit cell size of a transistor included in the electronic devices is reduced, electrical characteristics of the electronic devices are unavoidably deteriorated. As a result, a transistor including a buried word line has recently been proposed and developed.